flatpak: Add link to Audio management doc

Signed-off-by: Frédéric Danis <frederic.danis@collabora.com>

content/concepts/application-bundle-metadata.md

@@ -31,8 +31,8 @@ to requests from an app-bundle to a platform service.
 
 ### Audio management priorities
 
-Assume that the Apertis audio management component (which is outside
-the scope of this document) assigns priorities to audio streams based
+Assume that the Apertis [audio management]({{< ref audio-management >}}) component
+assigns priorities to audio streams based
 on [OEM]-specific rules, potentially including user configuration.
 
 Suppose the author of an app-bundle has a legitimate reason to have their